change: structure of GridDropdownColumn

lib/ui/css/grid.scss

@@ -412,6 +412,22 @@
                             }
                         }
 
+                        .ui-drop-span {
+                            margin: 0;
+
+                            >span {
+                                margin: var(--spacing-cell);
+                                display: block;
+                                overflow: hidden;
+                                text-overflow: ellipsis;
+                                white-space: pre;
+
+                                &.wrap {
+                                    @include wrap();
+                                }
+                            }
+                        }
+
                         .ui-drop-wrapper {
                             height: var(--row-height);
                             width: 100%;